Cosmologists Find Cleaner Way to Map Universe's Expansion
Researchers using the Dark Energy Survey discovered that focusing on young, star-forming galaxies dramatically reduces measurement errors in studies of dark energy and cosmic expansion. The technique cuts uncertainty by 50% without requiring complex new math, offering a faster path to more reliable maps of the universe's fate—crucial data for long-term space exploration and fundamental physics investments.
Originaltitel: Dark Energy Survey Year 3: Blue shear
Modeling the intrinsic alignment (IA) of galaxies poses a challenge to weak lensing analyses. The Dark Energy Survey is expected to be less impacted by IA when limited to blue, star-forming galaxies. The cosmological parameter constraints from this blue cosmic shear sample are stable to IA model choice, unlike passive galaxies in the full DES Y3 sample, the goodness-of-fit is improved and the $Ω_{m}$ and $S_8$ better agree with the cosmic microwave background. Mitigating IA with sample selection, instead of flexible model choices, can reduce uncertainty in $S_8$ by a factor of 1.5.